Annular ligaments (lat. annularia) are paired cartilaginous formations located in the trachea and bronchi. They consist of cartilaginous rings of an incomplete circle, connected by membranes. The annular ligaments maintain the patency of the airways, preventing them from collapsing during exhalation. Their number decreases from the trachea to the bronchi.
Annular ligaments of the trachea (lat. annularia trachealia) - 16-20 cartilaginous half-rings in the trachea. They support its frame and prevent the walls from collapsing.
The annular ligaments of the bronchi are located in the bronchi and their branches. Their number decreases as the bronchi branch. In small bronchi, ligaments are replaced by cartilaginous plates.
Thus, the annular ligaments play an important role in maintaining the patency of the airways, especially during exhalation. Their structure allows the airways to narrow and expand during breathing.